Wallwisher can be used to create an online noticeboard.

This  provides a very simple way to gather feedback from students, for example there are some thoughts here from year 7 on using a Wiki.  It is very simple to create a wall of  examples such as this one used with Year 7 Mathematics students. Students could collaborate to produce a wall of key facts for revision. Here is an example of a History teacher’s wall.

Ideas for Wallwisher in the classroom from Tom Barrett’s ‘Interesting Ways’ series.